Weeds – Introduction, Concept, Characteristics and Importance in Agriculture

 In the initial phases of life on Earth, the prevalence of undesirable plants was not extensive. Humans developed the practice of differentiating between weeds and crops based on economic activities. It has been suggested that there are close to 30,000 species that can be classified as weeds. These have co-evolved with crops and are deemed undesirable because of their capacity to outcompete cultivated plants that are intended for food and fiber production. It is widely accepted that all primary cultivated plants have originated from wild weeds. Several plant species that were previously utilized for ornamental, therapeutic, or feed purposes are currently classified as weeds. The crop ecosystem has undergone significant changes due to the use of high levels of fertilizers, intensive cropping practices, and modifications in cropping patterns. Weeds possess specific characteristics that enable them to thrive and persist in environments where many cultivated plants would ultimately perish. The existence of weeds may have multiple effects on human existence. Apart from their economic implications, these cause hay fever in humans and can also exhibit toxicity in livestock and wildlife. The impact of weeds on crop productivity varies based on certain factors such as type of weed species, density of weeds, duration of weed competition, and method of cultivation.